1. Field of the Invention
The present invention relates to a variable porcelain condenser in which a rotor electrode and a stator electrode are arranged through a ceramic dielectric member.
2. Description of the Prior Art
Before entering into detailed description of the present invention, cursory review will be made on one example of the variable porcelain condenser of the prior art with reference to FIG. 3 and FIGS. 4(a) and (b). In these Figures, reference numeral 12 indicates a rotor made of a metallic material, which is formed on its one side with a raised, generally semicircular rotor electrode 12b. Indicated at numeral 13 is a stator made of a ceramic dielectric member, which is concentrically formed on its one side with a generally semicircular stator electrode 17 by printing or calcining a silver paste or the like. On the other hand, numeral 15 indicates a stator terminal made of a metallic material, which is inserted or press-fitted into an insulating frame 14 made of an insulating molded member so that it is supported therethrough. Moreover, numeral 16 indicates an earth terminal made of a metallic material, and numeral 11 indicates a rotor shaft made of a metallic material.
Next, the method of assembling the variable porcelain condenser thus constructed will be described in the following.
First of all, the aforementioned stator 13 is so inserted into the aforementioned insulating frame 14 supporting the aforementioned stator terminal 15 therethrough that the stator electrode 17 formed on one side of the stator 13 and the leading end portion 15a of the stator terminal 15 come into contact with each other. Next, the aforementioned rotor 12 is so mounted that the aforementioned rotor electrode 12b comes into contact with the aforementioned stator 13. At this time, the stator 13 has its straight portions 13b retained on the straight portions 14b of the aforementioned insulating frame 14. Moreover, the aforementioned rotor shaft 11 is inserted into the respective center holes 12a, 13a, 14a and 16a of the aforementioned rotor 12, stator 13, insulating frame 14 and earth terminal 16 until its lower portion 11b projecting from the earth terminal 16 is caulked to be held in electric connection with the earth terminal 16. At this time, the aforementioned rotor shaft 11 has its journal 11a held by the stepped portion 12d of the aforementioned rotor 12 so that it is prevented from coming out. As a result, the rotor 12 and the aforementioned earth terminal 16 are electrically connected with each other through the aforementioned rotor shaft 11.
By turning the aforementioned rotor 12 through its adjusting groove 12c by means of a driver (although not shown) or the like, therefore, the opposing areas of the aforementioned rotor electrode 12b and stator electrode 17 can be varied at will so that an arbitrary capacity can be established from the aforementioned stator terminal 15 and rotor terminal 16.
However, the example of the prior art described above has a considerable number of parts and a complicated shape so that it is troubled by its automatic assemblage and finds it difficult to provide a variable porcelain condenser of higher performance at a more reasonable cost.